1. Field of the Invention
The present invention relates to method for aligning a printer and, more particularly, to a method of printing patterns for rapidly vertically aligning a bidirectional printer.
2. Background Art
A typical printer such as a dot matrix printer, an ink-jet printer or a plotter includes a printer head mounted on a carriage for printing a plurality of rows of dots in a single scan of the print carriage across a printable medium. The typical printer prints information serially one letter per unit of time and can be unidirectional or bidirectional. A bidirectional printer can print information on a printable medium in both directions, that is, from left to right in a first line, and then form right to left in a second line. As a result, the printing speed of a bidirectional printer is twice as fast as a unidirectional printer, which can only print information in one direction and that has a carriage that must be returned to a starting position for each new line of printed characters.
The printer head is typically mounted in a print cartridge within an assembly that is mounted on the carriage of the printer. Generally, full color or black and white printing or plotting requires that the carriage supporting the printhead be precisely aligned so as to begin printing information at a precise location on a printable medium. Proper alignment of the printer is necessary to counter irregularities due to forces resulting from the acceleration and deceleration of the carrier body caused by the motor. Otherwise, any misalignment of the carriage will result in a misregistration of print images, due to incorrectly placed ink, particularly when the printer is a multi-color type of printer. Unfortunately however, mechanical misalignment of the carriage in the printable scan axis (i.e., the x-axis) and in the carriage scan axis (i.e., the y-axis) is common in contemporary printers.
Typical techniques for alignment of printers are disclosed, by way of example, in U.S. Pat. No. 5,600,350 to Cobbs entitled Multiple Inkjet Print Cartridge Alignment By Scanning A Reference Pattern and Sampling Same With Reference to a Position Encoder, U.S. Pat. No. 5,448,269 to Beauchamp entitled Multiple Inkjet Print Cartridge Alignment for Bidirectional Printing By Scanning a Reference Pattern, U.S. Pat. No. 5,451,990 to Sorenson entitled Reference Pattern for Use in Aligning Multiple Inkjet Cartridge, U.S. Pat. No. 5,404,020 to Cobbs entitled Phase Plate Design for Aligning Multiple Inkjet Cartridges by Scanning a Reference Pattern, U.S. Pat. No. 5,350,929 to Meyer entitled Alignment System for Multiple Color Pen Cartridges, U.S. Pat. No. 5,297,017 to Haselby entitled Print Cartridge Alignment in Paper Axis, U.S. Pat. No. 5,250,956 to Haselby entitled Print Cartridge Bidirectional Alignment in Cartridge Axis, in which software is incorporated into the printer to allow a user to perform vertical and horizontal alignment of a printhead using a predetermined test pattern.
I have observed that many vertical alignment processes use a series of vertical line segments to calibrate a print cartridge. During calibration of a print cartridge the cartridge must delay its printing by an appropriate amount of time, thus allowing the print cartridge to adjust its X-axis location before printing. Many processes used for aligning a print cartridge waste excessive amounts of paper. I expect that using a printing pattern for vertically aligning a bidirectional printer that allows the quantity of wasted paper to be reduced and the speed of the alignment process to be increased will increase the efficiency of the alignment process.